This invention relates to valves used generally to communicate pneumatic commands to a variety of destinations. The machinery being controlled is usually predominantly hydraulic or pneumatic, such as industrial automation machines or robots, but is not limited to these fields. Communication between the machines' automatic controls and operators are normally accomplished by push-buttons or selectors, with visual indicators given feedback to the operators. However, when changing the desired operating command through to a particular destination, it was important that no inadvertent pulse commands be given to the wrong destinations while in the process of selecting the desired passageway to communicate pneumatic commands.
Because it is often necessary to quickly shut down machines being commanded by pneumatic signals, the activation of emergency shutdown commands should be brought about simply, preferably by pushing the control knob in. This way the operator can quickly hit the control knob with his hand or other body surface. This is particularly important when the operator's hand may be slippery due to contact with material being processed. Additionally, once the emergency position is engaged, the valve mechanism should require a positive action on the part of the operator to disengage from the emergency position.
It is known to provide a combined reciprocating and rotary valve having circumferentially spaced working ports. U.S. Pat. No. 3,520,327 shows such a structure. However, this structure shows a coil spring acting from a single rotational position upon the central spool. Additionally, the stop mode is engaged by holding in the handle to exhaust all ports. Letting go of the handle will return the valve to a command communicating mode. Finally, the valve uses a poppet type mechanism to control the flow of fluids.
As the complexity of the manual controls increases it has been a general practice to add push button valves and to accomplish the control with interconnecting tubing or circuits. With each additional moving part and circuit the change of malfunction is increased and the skill of people operating the manual controls must be greater. Many control valve manufacturers, in order to compete, are making cheaper manual valves which further increases the chance of malfunction. Manual controls that are duplicated on many machines are as follows: 1. manual mode with visual indicator; 2. automatic mode with visual indicator; 3. power air on with visual indicator; 4. power air off; 5. cycle start; 6. cycle stop; 7. reset; and 8. emergency stop, etc. . . .
Very little attention has been given to the design of these functions especially in regard to human error, circuit malfunction (pinched or broken tubes), or component failure. By far the most important function of the above is the Emergency Stop. Also operating personnel should be made to think prior to initiating any of the above functions. Power valves are usually designed to shift or not to shift in case of control air loss or emergency stop mode. Detented valves are used for clamps and sometimes spring return valves are used for drill heads, etc. The important things for emergency stop are as follows: 1. kill control air and positively exhaust; 2. be actuated fast and easy at any point of the machine cycle; 3. be mechanically detented off with no chance of inadvertent return. The important things for other functions is that the operator person may select prior to actuating any function and without bumping functions between his selections. It is believed that by using simple and reliable components a greater degree of control with less human error, and with less component and circuit failures, can be achieved.